1. Field of the Invention
The invention relates to a bicycle having a pedal crank drive and having an electrical auxiliary drive, which is connected to the pedal crank drive, and which has a wheel hub motor having a freewheel hub for the rear wheel.
2. Description of the Related Art
To provide advantageous design conditions for electrical auxiliary drives in bicycles, providing a wheel hub motor for the rear wheel, whose spokes engage directly on the wheel hub motor, is known. The pedal crank drive is connected to the freewheel hub of this wheel hub motor, wherein typically a shift transmission is interposed, to be able to provide an advantageous pedaling frequency range for a comparatively large speed range for the pedal crank. This means, if a gear shifter is provided, that a bicycle user must operate the gear shifter accordingly to be able to predefine advantageous operating conditions with respect to the pedal crank drive. These difficulties can be avoided by an automatic transmission, but an automatic transmission also cannot take influence on the operating point of the wheel hub motor resulting due to the motor load as a result of the travel resistance.
In addition, providing the front wheel of a bicycle with an electrical auxiliary drive is known (US 2005/067207 A1), wherein the possibility exists of also providing the rear wheel with an identical auxiliary drive. These auxiliary drives can be equipped with step-down transmissions which can be switched over, to allow an extensive adaptation of the auxiliary drives to the respective requirements. However, the design expenditure is substantially increased by the additional step-down transmissions.